Sealing devices which seal the space between a housing and a rotating shaft projecting to the outside from the housing, include known lip type sealing devices (for example, refer to Japanese Unexamined Patent Publication No. 2003-120821). The lip type sealing device is required to have pressure tightness for reliably, preventing leakage of a high-pressure sealed fluid and resistance to wearing and heating caused by sliding friction of the seal lip in contact with the rotating shaft.
On the other hand, in a lip type seal, one having a support ring for supporting a seal lip to maintain an appropriate contact area between a seal lip and a rotating shaft even in a high-pressure environment is known (for example, refer to Japanese Unexamined Patent Publication No. H10-325470).
The lip type sealing device disclosed in Japanese Unexamined Patent Publication No. H10-325470 is an oil seal, including, as shown in FIG. 1, a seal ring 100 made of rubber, having a fitted part 101 which is fitted into a hole 107a of a housing 107, an annular part 102 extending from the fitted part 101 inwardly in the radial direction, a cylindrical seal lip part 103 which extends to the oil side to be sealed on the right of the drawing from the annular part 102 and comes into contact with the rotating shaft 106, a metal-made reinforcement ring 104 embedded in the fitted part 101 and the annular part 102, and a metal-made support ring 105 embedded in an inner peripheral surface in the base region of the seal lip part 103.
The support ring 105 prevents the base region of the seal lip part 103 from deforming excessively toward the rotating shaft 106 side by receiving a pressure, and suppresses wearing and frictional heating due to an increase in the contact area between the seal lip part 103 and the rotating shaft 106.
The reinforcement ring 104 reinforces the fitted part 101 and the annular part 102 of the seal ring 100, and is in contact with the support ring 105 in the axial direction.
The above-described conventional oil seal is formed by integrally molding of the rubber seal ring 100 with the metal-made reinforcement ring 104 and the support ring 105 when forming the rubber seal ring 100.
However, if integrally molding the seal ring 100 with the reinforcement ring 104 and the support ring 105, the contact state between the seal lip part 103 and the rotating shaft 106 when the seal ring 100 is attached to the rotating shaft 106 varies according to variation in molding accuracy of the seal lip part 103. For example, when the seal lip part 103 excessively comes into contact with the rotating shaft 106, the seal lip part 103 deforms from the base region thereof and comes off from the support ring 105, and a gap may be formed between these. If a gap is formed between the support ring 105 and the seal lip part 103, the support ring 105 does not perform the role of supporting the base region of the seal lip part 103.
The seal lip part 103 of the conventional oil seal is provided with a support ring 105, so that it cannot follow the eccentricity of the rotating shaft 106, and wearing greatly progresses under the action of a high pressure.